You don't need deep pockets to get some pro-looking diffusion. In fact, a dollar is probably all it'll take. Here's Film Riot's Ryan Connolly to give you some tips on how to utilize an everyday shower curtain to soften light, as well as how to grade your footage to make it look more cinematic.
When footage has that unattractive "video-y" look, one major culprit is harsh lighting. In fact, many a cinematographer will tell you that it's the lighting, not (only) the camera, that gives images that coveted cinematic look. (I'm sure I'm not the only one who saved up several thousand dollars to buy a nice digital camera, dropped the ball on lighting, and wondered why my film didn't "look like a film.") Diffusing light is a great way to achieve that aesthetic -- if, in fact, a diffused look is what you're going for.
Now, depending on what kinds of stores you have in your town, you could potentially get a shower curtain for as little as a dollar, but even if you don't have a Dollar Store (or any variation thereof) near you, you won't be spending more than $10. And the great thing about a shower curtain, other than the fact that they come in a bunch of different opacities and colors, is that they're so big. You could use them to diffuse light coming from a large light source, or cut it up and use the pieces to diffuse multiple sources.
If shower curtains aren't your thing for whatever reason, there are a myriad of other materials you could use for diffusion, like T-shirts, bed sheets, Tupperware, visqueen, towels -- you could build your own panels that utilize diffusion material or even stretch some pantyhose over the back of your lens. There are virtually endless DIY methods for diffusing light that won't empty your wallet, so if you have any suggestions, please share them in the comments below. What works? What absolutely doesn't work? Let us know!